| 摘要 |
A cassette for a strip such as a tape or film, having a pair of spools between which the strip is wound and unwound, is provided with apparatus for counting and limiting the number of times the cassette is played. A feeler assembly is mounted for swinging movement on the cassette cover, between the rolls of strip on the spools, and has two feelers one of which rides on the outer periphery of one roll and the other of which rides on the outer periphery of the other roll. Upon winding and rewinding of the strip, therefore, the feeler assembly oscillates, and in doing so, it actuates an escapement which turns a toothed wheel. The toothed wheel, turning one unit of angular movement with each play of the cassette, records the number of plays by the rotated position of the wheel, which can be read through a window of the cassette, in the form of numerals on the wheel. Two wheels can be provided, one to count the number of plays, and the other bearing at least one abutment which stops the rotation of that other wheel, either by engagement with a fixed abutment on the cassette cover, or else by engaging and hence blocking the escapement in contact with an abutment surface on the wheel. The escapement can be so formed as to register the play only during a midportion thereof, thereby to prevent fraudulent extra use of the cassette by skipping the beginning or end of the strip. |
